The subject of this Phase I SBIR proposal is the development of a screening system that quantifies the effects of candidate psychoactive drugs across 16 different GPCRs in a single sample. Many endogenous GPCR ligands target multiple receptors. Specific biological effects are often achieved through a "selective non-selectivity" where a small subset of receptors is activated to varying degrees by a specific ligand. Similarly, many psychoactive drugs are only effective because they target multiple GPCRs. For multi-component diseases such as drug abuse, the path to therapeutic intervention would benefit from being able to screen compounds for their effects across a wide range of GPCRs and select drugs with the proper activation profiles. Conversely, drugs that activate unintended targets can have disastrous effects. These compounds would also benefit from being able to assess their specificity across a wide range of toxicologically relevant GPCRs. In order to identify compounds that inhibit or activate multiple receptors of interest, a system is needed that profiles these responses simultaneously. Primity has developed a novel GPCR assay, applicable to greater than 90% of all GPCRs, that will be combined with Primity's cellular barcoding platform (CellCode) to enable the simultaneous screening 16 GPCR targets in a single assay well. In order to combine these techniques, the GPCR assay will first be optimized for performance in a high-throughput flow cytometry screening environment. Next, sixteen cell lines expressing different GPCRs will be generated and optimized for performance in the assay. To multiplex these targets, each cell line will be barcoded with a unique genetic identifier such that all sixteen cell lines can be mixed, frozen, thawed, and analyzed simultaneously. As a final validation, the mixture will be tested with specific agonists to ensure each cell line accurately reports the pharmacology of the test agonists (EC50) and antagonists (IC50) in combination and individually. The completion of these studies will provide a unique method of assaying receptor activation in a highly multiplexed system that dramatically reduces the time and costs of performing GPCR screens, yet ensures highly significant data generation. PUBLIC HEALTH RELEVANCE: The mechanisms and consequences of drug abuse cross multiple biological targets. The system described here is a method of identifying the effects of novel therapies across a broad range of targets to find unexpected activities of known drugs, psychoactive substances, and to define the components of herbal therapies, leading to the selection and development of better therapeutic compounds.